Systematic review of methods and outcomes for measuring head movements during unperturbed gait in healthy people and those with neurological disorders, finding heterogeneous metrics, limited patient data, and reported differences such as altered acceleration and shock absorption but few studies…

While not offering molecular or therapeutic targets, the paper identifies candidate biomechanical biomarkers and measurement gaps that could inform clinical phenotyping, outcome measures, and rehabilitation strategies relevant to Parkinson's gait dysfunction and trial design.

The Head-Trunk System (HTS) is crucial for maintaining visual acuity and stabilizing the head during activities such as walking. However, no consensus exists on methods for measuring HTS movements during walking. Alterations in HTS function, particularly in head movement, are detectable even in the early stages of neurological disorders (PwND). Therefore, this study aimed to summarize the methods and tools used to evaluate head movements in healthy subjects (HS) and PwND during unperturbed linear gait. This systematic review followed the PRISMA Guidelines and the Cochrane Handbook; the protocol was registered on Open Science Framework. In November 2025, the search was conducted across Scopus, Embase, and PubMed. 27 studies were included after screening. Seventeen studies involved 522 HSs aged 17-80 years. Seven studies included PwND. Due to the heterogeneity of the included studies, only a qualitative analysis was conducted. Among HS, the most frequently reported outcome was sagittal plane head angular displacement, averaging 5-10°. In contrast, none of the studies involving PwND reported head angular displacement as an outcome. Other parameters included shock absorption, harmonic ratio, head acceleration, and speed. Significant differences were observed between HS and PwND. Our study reviewed all outcomes and methodologies used to assess head movements. Despite the heterogeneity of the outcomes, this review emphasizes the importance of evaluating head stability during gait by comparing HS and PwND. This could be significant for researchers in designing future studies and for clinicians planning exercises to enhance head stabilization during walking.